Glucagon-like peptide-1 (GLP-1) receptor agonists such as semaglutide and liraglutide are transforming diabetes and weight management, but their appetite-suppressing effects pose unique challenges for active individuals. Reduced hunger, delayed gastric emptying, and persistent fullness can make it difficult to consume adequate energy for exercise, potentially compromising performance and muscle preservation. Strategic nutritional planning becomes essential to balance medication benefits with training demands. This guide explores evidence-based approaches to fuelling workouts whilst taking GLP-1 medications, covering meal timing, macronutrient priorities, energy management, and when to seek medical advice for safe, effective exercise on these treatments.

How GLP-1 Medications Affect Appetite and Exercise Performance

Glucagon-like peptide-1 (GLP-1) receptor agonists, including semaglutide (Ozempic, Wegovy) and liraglutide (Saxenda, Victoza), are increasingly prescribed for type 2 diabetes management and weight loss. These medications work by mimicking the naturally occurring GLP-1 hormone, which regulates blood glucose levels by stimulating insulin secretion, suppressing glucagon release, and slowing gastric emptying. Importantly, GLP-1 receptor agonists also act on appetite centres in the brain, significantly reducing hunger and promoting earlier satiety.

For individuals engaging in regular physical activity, these appetite-suppressing effects can present unique challenges. Many patients report substantially reduced food intake, sometimes struggling to consume adequate calories even when attempting to eat. This marked decrease in appetite may lead to insufficient energy availability for exercise, particularly during moderate to high-intensity workouts. The delayed gastric emptying can also cause feelings of fullness or nausea that persist for hours after eating, making it difficult to time meals appropriately around training sessions. These gastrointestinal effects are often most pronounced during medication initiation and dose escalation periods.

Research suggests that whilst GLP-1 medications effectively promote weight loss, they may also contribute to loss of lean muscle mass alongside fat mass if nutritional intake is inadequate. This is particularly relevant for active individuals, as preserving muscle tissue is essential for maintaining metabolic health, functional capacity, and exercise performance. Some patients report reduced exercise tolerance, fatigue, or difficulty recovering from workouts. Evidence directly linking GLP-1 receptor agonists to impaired exercise performance is limited; reduced energy intake and gastrointestinal effects are likely the primary drivers of these symptoms, highlighting the importance of strategic nutritional planning when combining these medications with regular exercise.

Patients with pre-existing severe gastrointestinal conditions, including gastroparesis, should discuss these with their prescriber before starting GLP-1 medications.

Nutritional Strategies for Fuelling Workouts on GLP-1

Optimising nutrition whilst taking GLP-1 medications requires a thoughtful approach that prioritises nutrient density and protein intake. Given the significant appetite suppression, focusing on foods that provide maximum nutritional value per bite becomes essential. Protein should be the cornerstone of your dietary strategy, with current guidance suggesting 1.2–1.6 grams per kilogram of body weight daily for active individuals, and potentially higher for those engaged in resistance training. Adequate protein intake helps preserve lean muscle mass during weight loss and supports recovery from exercise. If you have kidney disease or are older with multiple health conditions, discuss appropriate protein intake with your healthcare provider.

Practical protein strategies include:

• Prioritising protein at each meal and snack (lean meats, fish, eggs, Greek yoghurt, cottage cheese, legumes)

• Consuming protein-rich foods first when appetite is limited

• Incorporating protein supplements (whey, casein, or plant-based powders) if whole food intake is insufficient

• Spreading protein intake throughout the day rather than concentrating it in one meal

Carbohydrates remain important for fuelling exercise, particularly moderate to high-intensity activities. However, the volume of carbohydrate-rich foods may need adjustment. Focus on easily digestible, nutrient-dense carbohydrate sources such as white rice, pasta, bananas, oats, and white potatoes, which are generally better tolerated than high-fibre options that may exacerbate feelings of fullness. For individuals with diabetes, it's important to monitor blood glucose responses to different carbohydrate sources and adjust choices accordingly.

For prolonged exercise sessions (over 60 minutes), consuming 30-60g of carbohydrate per hour may help maintain energy levels, particularly when appetite is reduced. For individuals experiencing significant nausea or early satiety, liquid nutrition options such as smoothies, milk-based drinks, or specialised sports nutrition products can provide essential calories and macronutrients in a more manageable form.

Healthy fats, whilst calorie-dense, should not be neglected. Small portions of nuts, nut butters, avocado, olive oil, and fatty fish provide essential fatty acids and fat-soluble vitamins. These foods can help meet energy requirements without requiring large volumes of food, though they should be consumed mindfully as they may slow digestion further.

Timing Your Meals and Snacks Around Exercise

Strategic meal timing becomes particularly important when taking GLP-1 medications due to their effects on gastric emptying and appetite patterns. The delayed gastric emptying characteristic of these medications means that food remains in the stomach longer, which can cause discomfort during exercise if meals are poorly timed. Most patients find that eating 2–3 hours before moderate to vigorous exercise allows sufficient time for partial digestion whilst still providing available energy for the workout.

For early morning exercisers, this timing can be challenging. If training first thing, consider a small, easily digestible snack 30–60 minutes beforehand, such as a banana with a tablespoon of nut butter, a slice of white toast with honey, or a small smoothie. Alternatively, some individuals may tolerate fasted morning exercise better on GLP-1 medications, particularly for low to moderate-intensity activities like walking or gentle cycling. However, fasted exercise is not appropriate for those taking insulin or sulphonylureas without specialist advice due to hypoglycaemia risk. This approach requires careful monitoring of energy levels and is generally not suitable for high-intensity or prolonged exercise sessions.

Post-exercise nutrition deserves particular attention. The anabolic window—the period following exercise when muscles are primed for nutrient uptake—remains important even with reduced appetite. Aim to consume a combination of protein (approximately 0.25-0.4g/kg body weight) and carbohydrates within 1–2 hours after exercise to support recovery and muscle protein synthesis. If solid food feels unappealing immediately post-workout, liquid options such as a protein shake with fruit, chocolate milk, or a recovery drink can be more palatable.

For longer exercise sessions (over 60 minutes), consider intra-workout fuelling with easily digested carbohydrates in liquid or gel form if tolerated. This can help maintain energy levels when appetite is suppressed.

Throughout the day, small, frequent meals or snacks (every 3–4 hours) may be better tolerated than traditional larger meals. This approach helps maintain steady energy levels, prevents excessive hunger or fullness, and ensures adequate total caloric intake. Keep convenient, nutrient-dense snacks readily available, such as Greek yoghurt, cheese with crackers, hard-boiled eggs, or protein bars, to support consistent fuelling despite reduced appetite signals.

Consider scheduling more demanding training sessions on days or times when gastrointestinal symptoms are lowest, which is often not immediately after medication doses or dose increases.

Managing Energy Levels and Preventing Low Blood Sugar

Maintaining stable energy levels whilst taking GLP-1 medications and exercising regularly requires vigilance, particularly for individuals with diabetes who face additional considerations regarding blood glucose management. GLP-1 receptor agonists lower blood glucose primarily through glucose-dependent mechanisms, meaning hypoglycaemia risk is relatively low when used as monotherapy. However, when combined with other glucose-lowering medications—particularly insulin or sulphonylureas—the risk of hypoglycaemia increases, especially during or after exercise.

Recognising the signs of low blood sugar is essential:

• Shakiness, trembling, or feeling jittery

• Sweating, particularly cold sweats

• Rapid heartbeat or palpitations

• Dizziness, light-headedness, or confusion

• Sudden fatigue or weakness during exercise

• Irritability or mood changes

For individuals with diabetes taking GLP-1 medications alongside other glucose-lowering therapies, regular blood glucose monitoring before, during (for prolonged exercise), and after physical activity is advisable. NICE guidance recommends that people with diabetes who exercise should be educated about hypoglycaemia prevention and management. Always carry fast-acting carbohydrates during exercise, such as glucose tablets, fruit juice, or energy gels, and know how to treat hypoglycaemia promptly (typically 15–20 grams of fast-acting carbohydrate, followed by rechecking blood glucose after 15 minutes).

Importantly, do not stop insulin or rapidly reduce insulin doses when starting a GLP-1 medication, as this can increase the risk of diabetic ketoacidosis (DKA). Any adjustments to insulin or sulphonylurea dosing should be supervised by your diabetes healthcare team.

If prescribed glucagon for severe hypoglycaemia, ensure family members or training partners know how to administer it. Call 999 if hypoglycaemia is severe or if the person becomes unresponsive.

Even for those without diabetes, the combination of reduced caloric intake and increased energy expenditure can lead to general fatigue, reduced exercise tolerance, or poor recovery. Warning signs that energy intake may be insufficient include:

• Persistent fatigue that doesn't improve with rest

• Declining exercise performance or inability to complete usual workouts

• Prolonged muscle soreness or delayed recovery

• Increased susceptibility to minor illnesses

• In women, menstrual irregularities

These symptoms may indicate Relative Energy Deficiency in Sport (RED-S), a condition requiring medical attention. If these symptoms occur, reassess your nutritional intake and consider consulting a registered dietitian with experience in sports nutrition and weight management medications. Adequate hydration is equally important, as GLP-1 medications can occasionally cause gastrointestinal side effects that may increase fluid requirements.

When to Seek Medical Advice About Exercise and GLP-1

Whilst GLP-1 medications are generally well-tolerated, certain symptoms or situations warrant prompt medical attention. Contact your GP or prescribing clinician if you experience:

• Severe or persistent nausea and vomiting that prevents adequate food or fluid intake

• Signs of dehydration (dark urine, dizziness upon standing, reduced urination)

• Unexplained, rapid weight loss exceeding 1–1.5 kg per week consistently

• Severe abdominal pain, particularly if accompanied by nausea or vomiting (potential pancreatitis)

• Pain in the right upper abdomen, fever, or yellowing of the skin/eyes (potential gallbladder problems)

• Recurrent hypoglycaemia, especially if taking other diabetes medications

• Significant decline in exercise capacity or persistent extreme fatigue

Call 999 immediately for:

• Chest pain or severe breathlessness during exercise

• Severe hypoglycaemia with altered consciousness

Call NHS 111 for urgent but non-emergency concerns when you cannot reach your GP.

For individuals with diabetes, regular review appointments are essential to monitor glycaemic control and adjust other medications as needed. As GLP-1 medications improve glucose management and weight decreases, doses of insulin or sulphonylureas often require reduction to prevent hypoglycaemia, but these adjustments should always be clinically supervised.

If you are pregnant, breastfeeding, or planning pregnancy, discuss with your healthcare provider as GLP-1 medications are generally not recommended during pregnancy or breastfeeding. For planned pregnancies, medications like semaglutide should be discontinued at least 2 months before attempting to conceive.

Consider requesting a referral to specialist services if:

• You're struggling to maintain adequate nutrition for your activity level

• You have complex diabetes management needs alongside intensive exercise training

• You're experiencing disordered eating patterns or concerning weight loss

• You require guidance on optimising body composition whilst taking GLP-1 medications

A registered dietitian can provide personalised nutritional strategies, whilst physiotherapists or BASES-accredited exercise professionals can help adapt training programmes to your current energy availability. Collaborative care between your GP, diabetes specialist nurse (if applicable), dietitian, and fitness professionals ensures safe, effective management of both your medication and exercise regimen.

Report any suspected side effects to the MHRA Yellow Card Scheme (yellowcard.mhra.gov.uk). Remember that GLP-1 medications are tools to support health improvements—they work best when combined with sustainable lifestyle modifications tailored to your individual circumstances and goals.

Frequently Asked Questions